Os spammers estão executando ataques de adivinhação de senha de força bruta no meu servidor (postfix no Debian). Eles já adivinharam duas senhas de usuários e começaram a enviar spam usando o meu servidor. Senhas alteradas e ataques atenuados (por enquanto), mas quero bloqueá-los completamente.
Eu instalei o fail2ban, mas por algum motivo ele não consegue detectar os ataques.
/etc/fail2ban/fail.conf contém:
[sasl]
enabled = true
port = smtp,ssmtp,submission,imap2,imap3,imaps,pop3,pop3s
filter = sasl
# You might consider monitoring /var/log/mail.warn instead if you are
# running postfix since it would provide the same log lines at the
# "warn" level but overall at the smaller filesize.
#logpath = /var/log/mail.log
logpath = /var/log/mail.warn
/etc/fail2ban/filter.d/sasl.conf contém:
# Fail2Ban configuration file
#
# Author: Yaroslav Halchenko
#
# $Revision$
#
[Definition]
# Option: failregex
# Notes.: regex to match the password failures messages in the logfile. The
# host must be matched by a group named "host". The tag "<HOST>" can
# be used for standard IP/hostname matching and is only an alias for
# (?:::f{4,6}:)?(?P<host>[\w\-.^_]+)
# Values: TEXT
#
failregex = (?i): warning: [-._\w]+\[<HOST>\]: SASL (?:LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed(: [ A-Za-z0-9+/]*={0,2})?\s*$
# Option: ignoreregex
# Notes.: regex to ignore. If this regex matches, the line is ignored.
# Values: TEXT
#
ignoreregex =
Quando eu executo o filtro em /var/log/mail.warn , ele produz resultados:
# fail2ban-regex /var/log/mail.warn '(?i): warning: [-._\w]+\[<HOST>\]: SASL (?:LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed(: [ A-Za-z0-9+/]*={0,2})?\s*$'
Running tests
=============
Use regex line : (?i): warning: [-._\w]+\[<HOST>\]: SASL (?:LOGIN|P...
Use log file : /var/log/mail.warn
Results
=======
Failregex
|- Regular expressions:
| [1] (?i): warning: [-._\w]+\[<HOST>\]: SASL (?:LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed(: [ A-Za-z0-9+/]*={0,2})?\s*$
|
'- Number of matches:
[1] 15293 match(es)
Ignoreregex
|- Regular expressions:
|
'- Number of matches:
Summary
=======
Addresses found:
[1]
123.169.7.222 (Sun Feb 25 06:40:18 2018)
123.169.7.222 (Sun Feb 25 06:40:21 2018)
...
185.173.176.157 (Fri Mar 02 10:12:46 2018)
185.173.176.157 (Fri Mar 02 10:13:15 2018)
185.173.176.157 (Fri Mar 02 10:13:43 2018)
185.173.176.157 (Fri Mar 02 10:14:11 2018)
185.173.176.157 (Fri Mar 02 10:14:41 2018)
185.173.176.157 (Fri Mar 02 10:15:13 2018)
185.173.176.157 (Fri Mar 02 10:15:42 2018)
185.173.176.157 (Fri Mar 02 10:16:13 2018)
185.173.176.157 (Fri Mar 02 10:16:42 2018)
185.173.176.157 (Fri Mar 02 10:17:10 2018)
Date template hits:
34294 hit(s): MONTH Day Hour:Minute:Second
0 hit(s): WEEKDAY MONTH Day Hour:Minute:Second Year
0 hit(s): WEEKDAY MONTH Day Hour:Minute:Second
0 hit(s): Year/Month/Day Hour:Minute:Second
0 hit(s): Day/Month/Year Hour:Minute:Second
0 hit(s): Day/Month/Year Hour:Minute:Second
0 hit(s): Day/MONTH/Year:Hour:Minute:Second
0 hit(s): Month/Day/Year:Hour:Minute:Second
0 hit(s): Year-Month-Day Hour:Minute:Second
0 hit(s): Year.Month.Day Hour:Minute:Second
0 hit(s): Day-MONTH-Year Hour:Minute:Second[.Millisecond]
0 hit(s): Day-Month-Year Hour:Minute:Second
0 hit(s): TAI64N
0 hit(s): Epoch
0 hit(s): ISO 8601
0 hit(s): Hour:Minute:Second
0 hit(s): <Month/Day/Year@Hour:Minute:Second>
Success, the total number of match is 15293
However, look at the above section 'Running tests' which could contain important
information.
Apesar de tudo isso, /var/log/fail2ban.log não mostra o bloqueio do endereço IP ofensivo.
Atualizar
Após sugestões, aumentamos o nível de registro. Isso mostra:
2018-03-02 12:47:55,920 fail2ban.filter : DEBUG Processing line with time:1519986602.0 and ip:185.173.176.157
2018-03-02 12:47:55,920 fail2ban.filter : DEBUG Ignore line since time 1519986602.0 < 1519987675.92 - 600
2018-03-02 12:47:55,920 fail2ban.filter : DEBUG Processing line with time:1519986635.0 and ip:185.173.176.157
2018-03-02 12:47:55,920 fail2ban.filter : DEBUG Ignore line since time 1519986635.0 < 1519987675.92 - 600
O jail.conf tem:
bantime = 600
maxretry = 3